Shallow Aquifer Potentiometric Surface Mapping in Kane County, Illinois
Kane County, on the west side of the Chicago area, is expected to see a surge in population of 70 percent by 2030, and county planners anticipate a growth in demand for water supplies. In response, local decision-makers commissioned the Illinois State Water Survey and the Illinois State Geological Survey to investigate the water resources of the region, including a project to map the potentiometric surface of shallow aquifers. Shallow aquifers considered include the unconsolidated sand-and gravel aquifers and the uppermost bedrock (i.e., the shallow bedrock aquifer). The study area includes Kane County and adjacent townships covering a total area of 1260 square miles. Water level measurements were obtained from a network of 1010 private, public, industrial, and commercial wells during September and October 2003. The collected data were used to construct potentiometric maps for three shallow aquifers: the Ashmore Tongue, the aggregated Glasford Formation sands, and the shallow bedrock.
Findings to Date: The potentiometric surfaces correlate closely with perennial stream configurations and land-surface topography. The Fox River and Marengo Ridge are the most influential features that determine regional groundwater flow patterns in the county. Groundwater flow west of the Fox River is predominantly to the south and east. East of the Fox River, flow is to the south and west. Groundwater withdrawals appear to have locally influenced the head surfaces, particularly in east-central and southeastern Kane County. Areas of relatively low head in the shallow bedrock aquifer may reflect large withdrawals from the aquifer, hydraulically connected units, and/or areas of significant discharge to the Fox River. The potentiometric maps can be used to characterize regional groundwater flow, identify areas of groundwater recharge and discharge, determine regional effects of groundwater withdrawals, and provide a baseline for comparison with future groundwater conditions. The maps have been useful in developing a conceptual model of groundwater flow and corresponding mathematical groundwater flow models for a wide range of analyses, including aquifer development scenarios.
Locke, R.A., II and S.C. Meyer. 2005. Kane County Water Resources Investigations: Interim Report on Shallow Aquifer Potentiometric Surface Mapping. Illinois State Water Survey Contract Report 2005-04, Champaign, IL.